Sequential flex mode for intrathecal infusion after continuous mode failure: a retrospective follow-up study for refractory cancer pain management.

BACKGROUND

Intrathecal drug delivery systems (IDDS) have long been recommended to relieve intractable cancer pain. Intrathecal treatment administered by continuous flow rate can result in suboptimal analgesia, despite daily dosage escalation. The distribution of drugs in the cerebrospinal fluid remains limited during intrathecal infusion.Thus, despite catheter localization close to the target level in the intrathecal space, it is challenging to maintain effective therapy despite a considerable increase in continuous pump flow rate. This led to the consideration of how to cover more dermatomes with an already implanted IDDS. Literature suggests that using large boluses, in addition to conventional continuous infusion, may help intrathecal drug spread. An innovative infusion mode, defined as the sequential flex mode, using a basal flow rate with large boluses, could provide better pain relief than the usual continuous flow rate mode.

METHODS

The sequential flex mode was used only for patients suffering despite a high continuous flow rate and a high daily drug dosage. The main objective of this retrospective monocentric study was to determine if patients achieved better pain relief with the sequential flex mode than the continuous flow rate mode.

RESULTS

53 patients were included. 71.7%±6.43% of the patients achieved at least 30% Numerical Rating Scale (NRS) pain reduction with the sequential flex mode, and in 52.5%±7.12% of the switches, the pain relief achieved was even greater than 50% NRS reduction. The median NRS evaluation showed a significant pain reduction after the switch from 6.4 (SD 2.0) to 3.3 (SD 2.2) (p<0.0001). Intrathecal morphine and ropivacaine daily doses remained stable in the switch success group around the switch. Adverse effects occurred in 12 switches out of 59 (20.3%±6.06%), and were non-serious in nature, most commonly increased anxiety.

CONCLUSION

The sequential flex intrathecal infusion mode may provide better pain relief when the continuous mode loses efficacy, as well as help to reduce daily dosage escalation.